This invention concerns the treatment of highly viscous hydrocarbon oils of high metals content, in order to convert these oils to a less viscous and consequently more easily transportable hydrocarbon mixture. Simultaneously the conversion according to the invention is such that the obtained hydrocarbon mixture has a reduced content of metals and asphalts and a more favorable distribution of its components. The latter may be subjected more easily to conventional refining treatments.
Numerous techniques for the thermal treatment of highly viscous crude oils have already been proposed in order to obtain an oil which can be transported more easily and converted to valuable products, but the success of these techniques was limited by the specifications that the resultant products must satisfy. In particular the conversion must not be too high in order to avoid the formation of excessive amounts of light hydrocarbons which are more difficult to transport; on the other hand, the quality of the obtained fractions must not be altered but, on the contrary, improved, so as to make them useful, for example, as catalytic refining charges; in this case, the content of such metals as vanadium and nickel must be reduced to the maximum extent, said metals being responsible for the deactivation of the refining catalysts. Moreover, as concerns the obtained heavy fraction, a too high conversion rate is detrimental to its stability (as defined by U.S. Standard ASTM 1661). Finally, the energy cost of the conversion must remain within reasonable limits. Among the techniques proposed up to now, illustrative examples are those described in U.S. Pat. Nos. 3,132,088, 3,193,487, 3,324,028, 3,338,818, and 4,005,006 and in the French Pat. No. 2,489,835.